Introduction: A Sub $10 MetaPrax Document Camera Setup for Video Conferencing
Published 20200803 by John E. Nelson firstname.lastname@example.org
Document cameras to be used in online meetings cost $60 to $150 from online retailers. With the sudden COVID-19 related transformation from in person learning to remote learning over the internet has come a high demand for document cameras. These cameras permit a student or coworker to demonstrate their work during a class or business meeting.The high cost prevents widespread use in K-12 and the demand for document cameras has outstripped supply even for colleges and universities. Document cameras are an integral part of cPLTL (cyber Peer-Led Team Learning cpltl.iupui.edu ).
I have to acknowledge that inspiration for this project was provided by the DIY Perks YouTube channel www.youtube.com/watch?v=C8pFkhkTvqo where Matt demonstrates how to use old laptop cameras as security monitors.
Document cameras I believe would be a good project for a group of makers. Over a weekend dozens of document camera systems can be made for a local school at low cost.
Step 1: Camera Module
I demonstrate how to build a sub $10 document camera system. The actual USB camera costs $4 and can be purchased in bulk from AliExpress. A word of caution, if you are buying one or two, the mailing costs can exceed the cost of the camera. It is better to make a bulk purchase of say 100 cameras and pay the air freight for speedier delivery. Also, if you order with a university or school mailing address the package may make it through customs a bit quicker. A single small package going to a residential address may languish in US customs for weeks before they pass it through.
The camera I chose is a 1280x1024 1.3 Mp laptop camera replacement with a USB dongle. A prewired 12” USB cable comes the the model I chose. I have used it with PC, Linux and Mac computers. I am still trying to figure out how to address the camera from a ChromeBook.Ideally the video conferencing software can present a split screen or picture in picture so that a person’s face can be shown along with the document.
As the USB cable is only 12 inches long consideration should be given to lengthening the cable by sacrificing a longer spare USB cable or a length of Ethernet cable could be interspersed, using one twisted pair for the signal lines, one pair for positive and one pair for the negative supply. Soldering the cables together and shrink insulation would be needed.My camera module followed the standard USB wiring color. Matt at DIY Perks demonstrates how to identify the wiring on an old camera module. If you purchase new, the USB cable included is easily identified by tracing the wires to the USB plug, all of which have a standard pinout. Not all camera boards may follow the accepted color code standard. I have not looked but perhaps a prewired USB cable with the correct pinout to attach to the camera board can be purchased.
Step 2: Camera Support Arm and Writing Board
I built a base from a piece of spare shelving (11.5” x 14”). Three rubber feet are placed on the base, one near the arm and two at the other end where your hand naturally rests during writing. The camera arm is made from four pieces of ½” x ¼” x 9” strips of wood available at home improvement stores or lumber yards or cut from larger stock if you have a table saw. Holes are drilled (best to use a fixture and drill press for accuracy) in each end to accept a 1 ½” #8 machine screw with a wing nut 32 threads per inch. Between the pieces of wood a washer with external teeth is placed to provide friction to hold the arm in place.
The arm is held to the base using a ½” x 1” a 1 ½” block. The block is held to the base from below using two drywall screws. All holes are pre-drilled to prevent splitting and the drywall screws are countersunk to prevent the base from scratching the desk on which it is placed. I chose to use a bit of all purpose (Gorilla) glue on the block and base screws to strengthen the bond and hopefully prevent splitting of the wood.
Step 3: Camera Module Shroud
The camera module shroud was cut in a T-shape from 3/16” thick birch plywood. A hole was drilled for the camera and the module was hot glued in place and sandwiched with spacers between the upper and lower pieces of plywood. If you have a laser cutter you can achieve better fit and finish than my quick hand cuts.. If you have a 3D printer I suggest printing a case to make attachment to the arm more convenient and to protect the camera board. Also cable routing and strain relief can be incorporated into a 3D printed case. Remember that the camera module is meant for a laptop and the long side of the board corresponds to horizontal. If the camera orientation is changed you would have to rotate the image in software and not all video conferencing software may support that function.
Step 4: Optional LED Light
I also demonstrate an LED strip attached to the arm to illuminate the writing surface. This LED strip is a standard soft white 12 volt DC strip with LEDs placed at 1.5” intervals which can be cut to length. The LEDs can be concealed under a strip of wood mounted on the horizontal arm. The LED strip is not needed. A desk lamp placed near the document camera works just as well.
Step 5: How Does It Work?
Finally I demonstrate the camera in use.
Video was captured from the document camera, cropped and clipped to condense the file size. Instructables requires that you upload the video to YouTube and then provide a link. I guess they don't want to host a lot of videos. Hopefully the link is durable.
A ruler is shown to give an idea of the camera resolution.